基于双窗全相位FFT双谱线校正电力谐波分析

基于快速傅里叶变换的电力谐波分析在非同步采样情况下存在频谱泄露，影响测量精度。为抑制频谱泄露对谐波分析的影响，分析对比了双窗全相位FFT与传统加窗FFT在抑制频谱泄露方面的特点，并通过计算证明了双窗全相位FFT在电力谐波分析中的独特优势。针对全相位频谱分析通常采用的时移相位差法存在计算量大、实时性差及存在相位模糊现象等不足，提出了一种基于双窗全相位FFT双谱线校正的谐波分析算法，利用基波频点附近的两条谱线幅值计算基波频率，进而推导了简洁实用的谐波幅值校正公式。该算法实现方便，且实时性优于相位差法。通过与传统加Hanning窗、Nuttall窗插值FFT的仿真对比验证了新算法具有更高精度，基于该算法的实验结果也验证了算法的有效性。

Double-spectrum-line correction method based on double-window all-phase FFT for power harmonic analysis

Spectrum leakage problem exists in the method of power harmonic analysis based on fast Flourier transform (FFT) under asynchronous sampling condition, which decreases the detection accuracy seriously. To reduce the influence of spectrum leakage on harmonic analysis, the features of double-window all-phase FFT and traditional wondowed FFT in restraining spectral leakage are analyzed and compared; the unique advantage of the double-window all-phase FFT in the application of power harmonic analysis is proved with calculation. Aiming at the fact that the time-shift phase difference spectrum correction method commonly used in all-phase FFT spectral analysis has some deficiencies such as large amount of calculation, poor real-time performance and phase ambiguity, the double-spectrum-line correction harmonic analysis algorithm based on double-window all phase FFT is proposed, which calculates the fundamental frequency according to the amplitudes of two neighbor spectrum lines near the fundamental frequency, and then the concise harmonic amplitude correction formulas are derived. The new algorithm is easy to be realized, and its real-time performance is better than that of the time-shift phase difference method. Simulation comparison was conducted; the results show that the proposed algorithm has higher precision compared with traditional Hanning-windowed and Nuttall-windowed interpolated FFT methods, at the same time, the actual experiment measurement results based on the algorithm also verify the effectiveness of the proposed algorithm.